I have an Apple IIgs ROM01 motherboard that had worked fine 2 years ago. Now I have reconnected it, it does not work anymore.
When I start the IIgs (without plug-in cards and drives connected) then it shows the startup screen "Apple IIgs ....ROM Version 01" and then jumps into the monitor and shows a *. It does not accept any keystrokes, also you cannot get into the control panel. Only the self-test can be called up, the graphic changes 18 times, then nothing more happens (it stops shortly before the text intermediate message 04000000 with a functioning IIgs).If a drive is connected, it flashes briefly when turned on, the start screen is displayed and nothing else happens. Otherwise as just described.
I have tested the CPU, it is ok. Is the RAM possibly defective?
If someone has a hint I would be very grateful, I am otherwise at a loss.